Grid in Nested Layout

side bar1 and side bar2 are collapsable .
when i collapsed side bar 1( i.e West Grid gets align to left of the Page)
when i collapsed side bar2 (i.e East Grid is not getting Aligned to Right grid is not covering whole page , its occupying a fixed length even though i removed grid panel width and height)
I am attaching the screen shots when left grid collapsed (left colllapse) how its behaving and when rigth bar collapsed (right collapse)how its behaving